Antisurge means for steam generating apparatus



2 Sheets-Sheet l P. ARANT ANTISURGE MEANS FOR 'STBAM GENERATINGAPPARATUS Filed Dec.

May 25, 1948.

W/W 7 Wk Z P. ARANT May 25, 1948.

ANTISURGE MEANS FOR STEAM GENERATING APPARATUS Filed Dec. 6, 1943 v 2Sheets-Sheet 2 Patented May 25, 1948 ANTISURGE MEANS FGR STEAMGENERATING APPARATUS Perry Arant, Alhambra, Califi, assignor to ClaytonManufacturing Company, Alhambra, Califi, a corporation of NevadaApplication December 6, 1943, Serial No. 513,093

3 Claims.

The present invention relates to intermittently operated steamgenerating apparatus of the type comprising a heating coil and a steamseparator, and in particular to means for preventing surging between theheating coil and steam separator during the intervals when the steamgenerating apparatus is shut down or idling.

In steam generating apparatus of the general type referred to, often,after the burner has been cut oil, sufficient radiant heat is given upby the walls of the firebox to cause a portion of the liquid in thelower end of the heating coil to evaporate. Such evaporation producessteam bubbles or slugs of steam which expand and cause liquid and/orvapor to be discharged, from the lower end of the heating coil into thesteam separator in a surging manner. In the majority of installations,such surges or pulsations are not objectionable, but in certain cases itis highly desirable to completely eliminate all surging.

One way of overcoming the aforementioned surging comprises theinstallation of an automatically operating bleeder valve in the line between the heating coil and the steam separator, the valve being arrangedso that it does not fully close but remains open to a predeterminedextent, or else closes fully but allows limited flow through suitableports, when the pump means supplying liquid to the heating coil is shutdown. In one form of the invention, the automatic valve is anelectrically operated solenoid valve connected in circuit with the motorthat drives the pump.

A further embodiment of the invention for overcoming the aforementionedsurging comprises the use of two pumps, one of which continues tooperate and circulate the liquid through the steam separator and heatingcoil so that no opportunity is afforded for the radiant heat toevaporate the liquid in the lower portion of the coil and cause it tosurge over into the separator.

Accordingly, the principal object of the invention is to eliminatesurging in steam generating apparatus between a heating coi1 (orequivalent means) and a steam separator connected with said heating coil(or equivalent means).

Another object of the invention is to provide automatic means forrestricting communication between a steam generating unit and a steamseparator to avoid surging during the inactive intervals of said steamgenerating unit.

A further object of the invention is to provide, in intermittentlyoperated steam generating apparatus, anti-surge means whichautomatically becomes efiective when the operation of the feed pump isdiscontinued,

Other objects of the invention will be apparent from the followingdescription taken in conjunction with the accompanying drawings inwhich:

Fig. 1 diagrammatically illustrates one form of the invention includinga solenoid valve for preventing surging between the heating coil and thesteam separator;

Fig. 2 is an enlarged elevational view, partly in section, of thesolenoid valve shown in Fig. 1;

Fig. 3 is a horizontal sectional View taken on the line 3-3 of Fig. 2;

Fig. 4 is a rear end View, partly inssection, of the solenoid valveshown in Fig. 2;

Fig. 5 is a vertical sectional view through the valve taken on the line'55 of Fig. 2; and

Fig. 6 is a view of a bleeder valve element which will permit the valveof Fig. 5 to completely close and still avoid surging.

Referring now to Fig. 1 of the drawings, the numeral I generallyindicates a combined pump means including a feed water supply pump F anda recirculating pump R. The pump means i is driven by a motor 2 througha belt 3. The motor 2 also drives a blower 4 through a belt 5. Theblower 4 is connected by a suitable conduit 5 with an air inlet chamber1 of a steam generating unit generally indicated by the numeral 8. Thesteam generating unit comprises a suitable burner nozzle 9 to which fuelis supplied through a conduit It. Fuel from the nozzle 9 is sprayed intoa firebox 9* contained within a housing H and is ignited by suitableelectrodes l2. The housing II contains a heating coi1 l3 of the pancaketype through which the liquid to be heated is circulated. A flue i4 isprovided at the upper end of the housing II for the escape of theproducts of combustion.

The feed pump F includes an intake feed manifold l5 the details of whichneed not be shown herein inasmuch as the pump means per se is not a partof the present invention. The inlet manifold I5 is connected to a feedwater tank it by a pipe line H. The pipe line I! has a manually operableshut-01f valve it) connected therein and a strainer [9 associated with astrainer blow-down valve 2% A predetermined minimum water level ismaintained in the feed .water tank It by a float mechanism 2|operatively associated with a float-controlled valve 22 and a watersupply pipe 23. The feed water tank i5 is vented to the atmosphere by apipe 24 having a shut-oh. valve 25 connected therein.

The recirculating pump R of the pump means l includes an intakerecirculating manifold 39 similar to the manifold l5. The manifold 30 isconnected by a pipe 3| with the lower end of a steam separator generallyidentified by the numeral 32. A manually controlled valve 33 in the lineserves to cut off communication between the steam separator 32 and therecirculating pump R. A strainer 34 is connected in the pipe line 3| andserves to prevent the passage of any foreign matter from the steamseparator 32 through the pipe 3| into the inlet manifold 36'. A strainercleanout valve 35 is connected with the strainer 34 as shown.

The feed pump F includes an outlet feed manifold 36 which is connectedby a pipe 31 to a mixing device 38. The recirculating pump R includes anoutlet recirculating manifold 39 which is connected by a pipe 40 withthe mixing chamber 38. The mixing chamber 38 is, in turn, connected by apipe 4| to the inlet end 42 of the heating coil I3. A manuallycontrolled shut-off valve 43 connected in the pipeline 4! controls theflow of liquid to the heating coiI l3. Hence, it will be clear that feedwater supplied through the pipe 31 and recirculating water suppliedthrough the pipe 40 are brought together in the mixing chamber 38 andthen delivered to the heating coil l3 through the pipe 4|. A pressuregauge 44 indicates the pressure in the mixing chamber 38 and, hence, inthe line 4| going to the heating coil IS. A valve 45 is connected withthe mixing chamber 38 for effecting blowing down of the heating coil [3.A pressure relief valve 46 is interposed in a pipe line 4! connectingthe mixing chamber 38 with the feed water tank Hi. The pressure reliefvalve 46 serves as a safety valve for the pump means I and is adapted toopen to relieve any excess pressure in the chamber 38 by passing liquiddirectly to the feed water tank [6.

The outlet end 48 of the heating coil I3 is connected to a thermostatfuel control device 49, which per se forms no part of the presentinvention, and said device is connected by a pipe 59 with the steamseparator 32, so that the heating coil discharges through said pipe intothe upper portion of said steam separator. Any of the liquid not flashedinto vapor in the steam separator 32 collects in the bottom thereof, andthe level of said liquid is indicated by a gauge glass In order toprevent the liquid level in the steam separator 32 from rising above apredetermined height; one end of a pipe 52 is con nected to saidseparator at a level corresponding to the maximum desired liquid level,and the other end of said pipe is connected with a heat transfer coil 53in the feed water tank I6. The coil 53 terminates in an ejector 54 whichserves to agitate the water in said tank while it is being heated. Thepipe 52 has a manually operable shut-oil valve 55 connected therein at apoint adjacent the steam separator 22- and on the inlet side of aconventional steam trap 56. A one-way check valve 51 is connected in thepipe 52 between the steam trap 56 and the feed water tank [6. The checkvalve 5'! is installed to allow flow in the pipe 52 only in a directionaway from the steam trap 56.

Steam is taken from the upper end of the steam separator 32 through apipe line 69 containing a manually operable shut-oif valve 6|. The pipeline 69 is connected with a load diagrammatically indicated at 62. Acondensate pipe 63 conducts condensate from the load 62 to the feedwater tank l6. A conventional steam trap 64 is connected in the line 63to prevent the return of any substantial quantities of steam from theload 62 to the feed water tank IS. The steam separator 32 is alsoprovided with a pressure gauge 65, a safety valve 66 and a blow-off ordrain valve 61.

An electromagnetically operated valve 79 is connected in the line 59between the outlet end 48 of the heating coil l3 and the steam separator32. The valve 19 is shown in detail in Figs. 2 to 5, inclusive, to whichreference will now be made.

As will be apparent from Fig. 5, the valve 19 comprises a body 1| havingan inlet chamber 72 and an outlet chamber 13. The flow of fluid betweenthe chambers 12 and I3 is controlled by a movable valve element 14, ofthe double poppet type. The element 14 includes spaced heads 76 adaptedto cooperate with seating surfaces 16 to restrict the flow through thevalve 19. One of the features of the valve 19, which is attained bystructure which will be described more fully hereinafter, is that theelement 14 is limited in its closing movement to prevent completeclosure of the valve in order to provide communication at all timesbetween the heating coil l3 and the steam separator 32. Hence, the headportions T5 are not intended to seat and form a seal with the heatingsurfaces 16 as they would normally do.

The valve body 70 is provided with a threaded opening in which a plug1'! is inserted after the valve element 14 has been passed therethrough.A threaded opening 18 in the body 10 is aligned with the plug 11 and acap member 19 is threaded into said opening. The cap member 19 isexternally shouldered at 80 and said shoulder is adapted to seat upon ahorizontal flange 8| (Fig. 2) projecting from a bracket 82. The cap 19includes a threaded portion 83 which projects through an opening 84 inthe flange BI and a lock nut 85 threaded onto the portion 83 and jammedagainst the underside of the flange 8| serves to mount the valve 19 uponthe bracket 82. A valve stem 86 projects through the cap 19 and has itsupper end provided with a flanged sleeve 81 which provides a. detachableconnection between said stem and the valve element H. A fluid-tight sealis maintained around the valve stem 86 by a stufllng box structuregenerally indicated by the numeral 88 assooi ated with the cap 19. Aspring 89 surrounds the stem 86 and one end thereof engages saidstuffing box and its opposite end engages a Washer 99. A nut 9| isthreaded upon the stem 86 and engages the washer 90. The nut 9| isadjustable on the stem 86 to vary the tension of the spring 89 urgingthe valve element 14 toward closed position.

The bracket 82 previously referred to is secured to a casing 92 (Fig. 2)by screws 92*. The casing 92 houses a conventional electromagnet 93having a movable armature or core 94. The core 94 has depending arms 94to which a lever 96 is pivotally connected at one end by a pin 96. Thelever is fulcrumed intermediate its length upon a pin 9'! carried by anarm 98 depending from the bracket 82. The free end of the lever 96 isprovided with a slot 99 adapted to receive the lower end of the valvestem 86. The slotted end of the lever 95 is provided with curved bossesengaged with the lower side of an adjusting nut l9l carried by the valvestem 86 and held against rotation by the cotter pin I02. A stop memberI03 (Fig. 2) in the form of a bolt is threaded into an opening H34 inthe bracket 82 and the head thereof is engaged by the lever 95 at apoint intermediate the pins 95 and 91. A look nut I05 maintains the stopH33 in any desired position of adjustment.

The electromagnet $53 is arranged so that when it is energized the core94 is forced downwardly causing the lever 95 to fulcrum about the pin 91and efiect an upward movement of the valve stem 88 and the element I lthrough the engagement of the curved bosses I00 with the nut I0l. Upwardmovement of the element is, of course, opens the valve 79 to its wideopen position. On the other hand, when the electromagnet 93 is:deenergized, the spring 89 willmove the valve stem 86 downwardly andtend to close the valve, but by suitably adjusting the stop member I03it is possible to limit the extent of closing of the valve to any degreedesired. Normally the stop IE3 is so adjusted that it will prevent thespring 89 from completely closing the valve 10. The object of thisarrangement is to restrict communication between the heating coil I3 andthe steam separator 32, to prevent surging as will be explainedhereinafter.

The electromagnetically operated valve Iii is connected in a circuit inparallel with a conventional pressure-responsive switch, generallyindicated by the numeral IIli (Fig. 1), for automatically controllingthe motor 2 which drives the pump means I and the blower i. Thepressure-responsive switch IIll includes a diaphragm III and a linkageIE2 for separating contacts H3 and N4 of said switch when a given steampressure is attained in the steam separator 32. The details of thepressure-responsive switch are unimportant inasmuch as an suitable orconventional presure-responsive switch can be used.

Current for operating the motor 2 is supplied through lines H5 and H6connected with a manually operable switch Ii'i. When the switch Ill isclosed, a lead IE8 connects the line H5 with the contact H3 and a leadIISi, including a relay coil IZI], connects the line HQ with the othercontact N4 of the switch Hi). The relay coil I20 controls a switch l2!arranged in the circuit between the electromagnetically operated valveii) and the manually operated switch I W. The electromagnet 93 of thevalve I0 is connected to the line H5 by a lead 22 and to the line He bya lead E23. It will, therefore, be apparent that the electromagnet 93and the motor 2 are connected in the circuit in parallel.

Normally, the contacts I I3 and Ild of the pressure switch I Ill areclosed. and when the manually operated switch I ii is closed the relayI20 will be energized, closing the switch IZI so that theelectromagnetically operated valve 19 and the motor 2 simultaneouslyreceive operating current. As a result, the motor 2 starts to drive thepump means I and the blower i, and the valve it! opens wide. However,the pressure-responsive switch III] is arranged so that when apredetermined steam pressure is developed in the steam separator 32 itcan interrupt the flow of current to the motor 2 and efiect incompleteclosing of the valve I0 through the lines H5 and M6 by deenergizing therelay are, thereby opening the switch I2I, not withstanding the factthat the manually 0perated switch I ii is closed.

When the steam generating unit 8 is shut down manually by opening theswitch I i'!, or as a result of the automatic operation of thepressure-responsive switch M0, the solenoid operated valve '10 willtend. to close simultaneously with the stopping of the motor 2, inasmuchas they are connected in parallel, as previously pointed out. Thestopping of the pump means I, of course, interrupts forced circulationof liquid through the heating coil II. The burner 9 is automaticallyshut off by the thermally responsive control means 49. Usually,sufiicient radiant heat remains in the firebox 9 after the burner 9 hasbeen shut down to cause a portion of the liquid in the lower end of theheating coil I3 to be vaporized thereby. The vapor thus formed normallytends to leave the heating coil I3 causing intermittent surging ofliquid over into the steam separator 32, which is highly undesirable incertain installations. Any tendency for such surging is overcome by thepresent system due to the fact that the valve 10 is permitted to remainslightly open after the steam generating unit 8 has been shut down. Suchslight opening of the valve ll] provides a bleeding action whichdefinitely restricts the flow of liquid and/or vapor into the steamseparator 32 to such extent that all surging is eliminated. At the sametime the bleeding action also prevents any possibility of a substantialamount of steam being generated and remaining in the heating coil I3,any such steam tending to pass over into the steam separator 32 becausesaid separator is under a lower pressure than said heating coil.

The rate at which vapor and/or liquid is permitted to pass from theheating coil I3 to the steam separator 32 (when the unit 8 is shut down)is determined by the extent of opening of the valve I0, and this can bevaried to suit the requirements of individual steam generating units bysuitably adjusting the stop I03.

It will be understood that any excess liquid accumulating in the steamseparator 32 will be removed through the steam trap 56 and returned tothe feed water tank I6 through the pipe 52. It will also be understoodthat the circulating pump R withdraws water from the separator 32 andrecirculates it through the heating coil I3.

The valve shown in Fig. 5 is, in efiect, a bleeder valve because it doesnot completely close. It will be apparent that the results accomplishedby this valve can also be achieved by a valve which does completelyclose, provided that the valve is constructed to permit the liquid tobleed therethrough to avoid surging when the valve is in its fullyclosed position. Thus, Figure 6 discloses a modified valve element 14similar to the valve element 14 shown in Figure 5, except that the valveelement I l has the head portions 15 thereof pierced by a plurality ofbleeder ports I60. It will be apparent that when a solenoid valveutilizing the element I l is used, in lieu of the valve 10, such valvecan be completely closed and surging will be avoided by the restrictedflow afforded by the ports I60. Any number of ports I60 may be employedand their size may be varied in accordance with the requirements of anindividual steam generating unit. Maniiestly, if the element I4 issubstituted in the valve ill the means employed for limiting the closingmovement of said valve may be dispensed with to permit engagement of theheads I5 with the seats I6.

It will be understood that various changes may be made in the means andsystem disclosed herein to eliminate surging without departing from thespirit of the invention or the scope of the annexed claims.

I claim:

1. Steam generating apparatus comprising: a

steam generating unit including conduit means having an inlet for liquidto be heated and an outlet for said liquid; pump means for supplyingliquidto said inlet; an electric motor driving said pump means; a steamseparator; a pipe line conmeeting the outlet of said conduit means withsaid steam separator; an electrically operated valve connected in saidpipe line, said valve being connected in a circuit in parallel with saidpumpdriving motor and arranged to close to a predetermined extent uponstopping of said motor to thereby restrict flow through said pipe lineand thus prevent surging of liquid and/or vapor from said conduit meansover into said steam separator,

2. Steam generating apparatus comprising: a steam generating unitincluding conduit means having an inlet for liquid to be heated and anoutlet for said liquid; pump means for supplying liquid to said inlet;an electric motor driving said pump means; a steam separator; apressure-responsive switch having its pressure-responsive portionconnected with said steam separator and arranged to open upon attainmentof a predetermined pressure in said steam separator; a pipe lineconnecting the outlet of said conduit means with said steam separator;an electrically operated valveconnected in said pipe line, said valvebeing connected in a, circuit in parallel with said pump-driving motor,said pressure-responsive switch being connected in said circuit tointerrupt the flow of current to said motor and electricallyoperatedvalve upon attainment of said predetermined pressure, and saidelectrically-operated valve being arranged to restrict flow through saidpipe line upon said interruption of flow of current, to thus preventsurging of liquid and/or vapor from said conduit means over into saidsteam separator.

3. Steam generating apparatus comprising: a steam generating unitincluding conduit means having an inlet for liquid to be heated and anoutlet for said liquid; pump means for supplying liquid to said inlet;an electric motor driving said pump means; a steam separator; a pipeline connecting the outlet of said conduit means with said steamseparator; an electrically operated valve connected in said pipe line,said valve being connected in a circuit in parallel with saidpumpdriving motor; a relay controlling the supply of current to saidmotor and electrically operated valves; a switch connected with saidrelay controlling the actuation thereof; and 'a pressure-responsivemeans connected to said steam separator and arranged to open said switchin response to a predetermined steam pressure in said steam separator,said relay and switch being so connected that opening of the switchcauses the relay to interrupt flow of current to said valve and pump,said electrically operated valve being arranged to restrict flow throughsaid pipe line upon interruption of the circuit to said relay and thusprevent surging of liquid and/or vapor from said conduit means over intosaid steam separator.

PERRY ARANT.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,559,763 Nicholson Nov. 3, 19251,883,293 Jacobus Oct. 18, 1932 1,898,196 Lucke Feb. 21, 1933 2,142,984Thurman Jan. 3, 1939 2,199,214 Vorkauf Apr. 30, 1940 2,201,618 La MontMay 21, 1940 2,210,822 Stilwe1l Aug. 6, 1940 2,217,635 Bailey et al Oct.8, 1940 2,227,349 Kerrick Dec. 31, 1940 FOREIGN PATENTS Number CountryDate 28,099 Great Britain Dec. 6, '1913

